Operation methods of communication node supporting direct communications in network

ABSTRACT

Disclosed are operation methods of communication node supporting direct communications in network. The operation method comprises obtaining scheduling information configured for the direct communications from a first base station; identifying modulation and coding scheme (MCS) information and radio resource information included in the scheduling information; and transmitting, to a second UE, a first message to which a MCS indicated by the MCS information is applied through radio resources indicated by the radio resource information. Therefore, performance of a communication system can be enhanced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priorities to Korean PatentApplication No. 10-2015-0134453 filed on Sep. 23, 2015, Korean PatentApplication No. 10-2015-0152151 filed on Oct. 30, 2015, Korean PatentApplication No. 10-2015-0180959 filed on Dec. 17, 2015, Korean PatentApplication No. 10-2016-0082897 filed on Jun. 30, 2016, and KoreanPatent Application No. 10-2016-0119881 filed on Sep. 20, 2016 in theKorean Intellectual Property Office (KIPO), the entire contents of whichare hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to direct communication technologies, andmore particularly, to operation methods of a communication nodesupporting vehicle communications based on a cellular system.

2. Related Art

A wireless access for vehicular environment (WAVE) protocol may be aprotocol supporting vehicle communications and support vehicle toeverything (V2X) communications. The V2X communications may includevehicle to vehicle (V2V) communications, vehicle to infrastructure (V2I)communications, vehicle to pedestrian (V2P) communications, in-vehiclenetworking (IVN) communications, and so on.

According to the WAVE protocol, seven channels may be supported in 5.85to 5.925 gigahertz (GHz) frequency band (i.e., 75 megahertz (MHz)bandwidth). The seven channels may be used for the V2X communications.One channel among the seven channels may be used for transmitting andreceiving control information and may be referred to as a controlchannel (CCH). The remaining six channels among the seven channels maybe used for traffic safety related services, general commercialservices, and so on, and may be referred to as a service channel (SCH).

In vehicle communication environments, coverage (e.g., communicationrange) of a roadside unit (RSU) may be overlapped with coverage of anadjacent RSU in order to guarantee continuity of services. A frequencyused by the RSU may be different from a frequency used by the adjacentRSU. In this case, if services between the RSU and an onboard unit (OBU)and services between OBUs each of them belongs to different coverage aresimultaneously provided, frequency interference may be occurred in asingle physical layer.

Meanwhile, this description on the related arts is written forunderstanding of the background of the present disclosure. Thus,information on other than conventional technologies, which are alreadyknown to those skilled in this technology domain to which thetechnologies of the present disclosure belong, may be included in thisdescription.

SUMMARY

Accordingly, embodiments of the present disclosure are provided tosubstantially obviate one or more problems due to limitations anddisadvantages of the related art. The embodiments of the presentdisclosure provide operation methods of a communication node supportingvehicle communications based on a cellular system.

In accordance with the embodiments of the present disclosure, anoperation method of a first user equipment (UE) supporting directcommunications in a communication network is provided. The operationmethod comprises obtaining scheduling information configured for thedirect communications from a first base station, wherein the first UEbelongs to coverage of the first base station; identifying modulationand coding scheme (MCS) information and radio resource informationincluded in the scheduling information; and transmitting, to a secondUE, a first message to which a MCS indicated by the MCS information isapplied through radio resources indicated by the radio resourceinformation.

Here, a state of the first UE may be a radio resource control (RRC)connected state or a RRC idle state.

The scheduling information may be shared in the first base station and asecond base station, and the second UE belongs to coverage of the secondbase station.

The radio resources indicated by the radio resource information may beconfigured based on a speed of a vehicle in which the first UE islocated, vehicle density in a zone to which the first UE belongs, orservice coverage of the direct communications.

The radio resource information may indicate radio resources which areselected by the first base station in a direct communication resourcepool when a mode1 manner is used. Alternatively, the radio resourceinformation may indicate the direct communication resource pool when amode2 manner is used.

The MCS information may indicate a MCS index or a MCS range each of themis configured by the first base station.

The MCS indicated by the MCS information may be configured based on aspeed of a vehicle in which the first UE is located, vehicle density ina zone to which the first UE belongs, or service coverage of the directcommunications.

Here, communications between the first base station and the first UE maybe performed through a Uu interface, and the direct communicationsbetween the first UE and the second UE may be performed through a PC5interface.

The first base station may be a first roadside unit (RSU) belonging to avehicle communication network, the first UE may be a first onboard unit(OBU) belonging to the vehicle communication network, and the second UEmay be a second OBU belonging to the vehicle communication network.

In addition, the operation method may further comprise obtaining, fromthe first base station, a direct communication resource pool; performinga monitoring operation on radio resources belonging to the directcommunication resource pool; and receiving, from the second UE, a secondmessage based on the monitoring operation.

In addition, the operation method may further comprise requesting, tothe first base station, allocation of additional radio resources for thedirect communications when the radio resources are unavailable;obtaining, from the first base station, additional radio resourceinformation; and transmitting, to the second UE, a third message throughthe additional radio resources indicated by the additional radioresource information.

The first UE may request the allocation of the additional radioresources to the first base station based on a random access procedure,a scheduling request procedure of a physical uplink control channel(PUCCH), or a buffer status report (BSR) procedure.

The additional radio resources may be selected among remaining radioresources except for radio resources, which are used for transmittingthe first message, in the direct communication resource pool.

Furthermore, in accordance with the embodiments of the presentdisclosure, an operation method of a first user equipment (UE)supporting direct communications in a communication network is provided.The operation method comprises, when the direct communications betweenthe first UE and a second UE are ended, transmitting a first messagerequesting end of the direct communications to a first base station; andperforming, for the end of the direct communications, a releaseoperation of radio resources with the first base station or a releaseoperation of radio resource control (RRC) connection with the first basestation, wherein the first UE belongs to coverage of the first basestation, the first UE operates in a RRC connected state when the releaseoperation of the radio resources is performed, or the first UE operatesin a RRC idle state when the release operation of the RRC connection isperformed.

In addition, the operation method may further comprise, when the directcommunications between the first UE which operates in the RRC connectedstate and the second UE are requested, requesting allocation of radioresources for the direct communications to the first base station;obtaining radio resource information from the first base station; andtransmitting a second message to the second UE through radio resourcesindicated by the radio resource information.

In addition, the operation method may further comprise, when the directcommunications between the first UE which operates in the RRC idle stateand the second UE are requested, selecting radio resources in a directcommunication resource pool which is obtained from the first basestation; and transmitting a third message to the second UE through theselected radio resources.

The direct communication resource pool may be configured based on aspeed of a vehicle in which the first UE is located, vehicle density ina zone to which the first UE belongs, or service coverage of the directcommunications.

The direct communication resource pool may be shared in the first basestation and a second base station, and the second UE belongs to coverageof the second base station.

Here, a modulation and coding scheme (MCS) which is applied to the thirdmessage may be configured based on a speed of a vehicle in which thefirst UE is located, vehicle density in a zone to which the first UEbelongs, or service coverage of the direct communications.

The first base station may be a first roadside unit (RSU) belonging to avehicle communication network, the first UE may be a first onboard unit(OBU) belonging to the vehicle communication network, and the second UEmay be a second OBU belonging to the vehicle communication network.

According to the embodiments of the present disclosure, the vehiclecommunications (e.g., V2V communications, V2I communications, V2Pcommunications, IVN communications, and so on) can be supported based onthe cellular system. In addition, a self-driving system, an intelligenttransportation system (ITS), and so on can be efficiently established.Therefore, performance of a communication system can be enhanced.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present disclosure will become more apparent bydescribing in detail embodiments of the present disclosure withreference to the accompanying drawings, in which:

FIG. 1 is a conceptual diagram showing embodiments of a wirelesscommunication network;

FIG. 2 is a block diagram showing embodiments of a communication nodeconstituting a wireless communication network;

FIG. 3 is a concept diagram showing a first scenario of D2Dcommunications;

FIG. 4 is a concept diagram showing a second scenario of D2Dcommunications;

FIG. 5 is a concept diagram showing a third scenario of D2Dcommunications;

FIG. 6 is a concept diagram showing a fourth scenario of D2Dcommunications;

FIG. 7 is a flow chart showing a method for transmitting a periodicmessage performed in a communication node;

FIG. 8 is a concept diagram showing embodiments of a vehiclecommunication network;

FIG. 9 is a concept diagram showing deployment scenarios of a cellularcommunication network;

FIG. 10 is a concept diagram showing deployment scenarios of a vehiclecommunication network;

FIG. 11 is a sequence chart showing embodiments of a communicationmethod performed by a communication node in a vehicle communicationnetwork;

FIG. 12 is a sequence chart showing embodiments of a communicationmethod based on gaze communications (or, look and link communications)in a vehicle communication network;

FIG. 13 is a timing diagram showing embodiments of a method fortransmitting a message through PRB; and

FIG. 14 is a timing diagram showing embodiments of a method forrepetition transmission of data.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure may be modified in various ways and the presentdisclosure may include various embodiments. The embodiments will beshown in figures and described in detail. However, the presentdisclosure is not limited to specific embodiments. It should beunderstood that the present disclosure includes all modifications,similar embodiments, and alternative embodiments belonging to idea andtechnical scope thereof.

The terms “first, second, and so on” will be used for describing variouselements. However, the elements are not limited thereto. These terms areonly used to distinguish one element from another. For example, a firstelement could be termed a second element, and, similarly, the secondelement could be termed the first element, without departing from thescope of the present disclosure. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. On the contrary, in the case that an element is referred to asbeing “directly connected” or “directly coupled” to another element, itwill be understood that there are no intervening elements.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this present disclosure belongs.It will be further understood that terms, such as those defined incommonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

Hereinafter, embodiments of the present disclosure will be described ingreater detail with reference to the accompanying drawings. In order tofacilitate general understanding in describing the present disclosure,the same components in the drawings are denoted with the same referencesigns, and repeated description thereof will be omitted.

A wireless communication network to which embodiments according to thepresent disclosure are applied will be described. The wirelesscommunication network to which the embodiments according to the presentdisclosure are applied is not limited to description below, and theembodiments according to the present disclosure may be applied tovarious wireless communication networks. The wireless communicationnetwork may indicate a wireless communication system.

FIG. 1 is a conceptual diagram showing embodiments of a wirelesscommunication network.

As shown in FIG. 1, a wireless communication network 100 may include aplurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2,130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Each of the plurality ofcommunication nodes may support at least one communication protocol. Forexample, each of the plurality of communication nodes may support a codedivision multiple access (CDMA) based communication protocol, a widebandCDMA (WCDMA) based communication protocol, a time division multipleaccess (TDMA) based communication protocol, a frequency divisionmultiple access (FDMA) based communication protocol, an orthogonalfrequency division multiplexing (OFDM) based communication protocol, anorthogonal frequency division multiple access (OFDMA) basedcommunication protocol, a single carrier-frequency division multipleaccess (SC-FDMA) based communication protocol, a non-orthogonal multipleaccess (NOMA) based communication protocol, a space division multipleaccess (SDMA) based communication protocol, a radio access technology(RAT) based communication protocol supporting multiple access based onbeamforming technologies by massive antenna, and so on. Each of theplurality of communication nodes may have following structure.

FIG. 2 is a block diagram showing embodiments of a communication nodeconstituting a wireless communication network.

As shown in FIG. 2, a communication node 200 may include at least oneprocessor 210, a memory 220, and a transceiver 230 connected to anetwork and performing communication. In addition, the communicationnode 200 may further include an input interface unit 240, an outputinterface unit 250, a storage 260, and so on. The respective componentsincluded in the communication node 200 may be connected via a bus 270 tocommunicate with each other.

The processor 210 may execute a program command stored in the memory 220and/or the storage 260. The processor 210 may be a central processingunit (CPU), a graphics processing unit (GPU) or a dedicated processor inwhich the methods according to embodiments of the present disclosure areperformed. Each of the memory 220 and the storage 260 may include avolatile storage medium and/or a nonvolatile storage medium. Forexample, the memory 220 may include a read only memory (ROM) and/or arandom access memory (RAM).

As re-shown in FIG. 1, each of the plurality of communication nodes maybe a base station or a user equipment (UE). Each of a first base station110-1, a second base station 110-2, and a third base station 110-3 mayform a macro cell. Each of a fourth base station 120-1 and a fifth basestation 120-2 may form a small cell. The fourth base station 120-1, aUE3 130-3, and a UE4 130-4 may belong to coverage of the first basestation 110-1. A UE2 130-2, the UE4 130-4, and a UE5 130-5 may belong tocoverage of the second base station 110-2. The fifth base station 120-2,the UE4 130-4, the UE5 130-5, and a UE6 130-6 may belong to coverage ofthe third base station 110-3. The UE1 130-1 may belong to coverage ofthe fourth base station 120-1. The UE6 130-6 may belong to coverage ofthe fifth base station 120-2.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and120-2 may be referred to as a NodeB, an evolved NodeB (eNodeB), a basetransceiver station (BTS), a radio base station, a radio transceiver, anaccess point, an access node, a road side unit (RSU), a radio remotehead (RRH), a transmission point (TP), a transmission and receptionpoint (TRP), a relay, and so on. Each of the plurality of UEs 130-1,130-2, 130-3, 130-4, 130-5, and 130-6 may be referred to as a terminal,an access terminal, a mobile terminal, a station, a subscriber station,a mobile station, a portable subscriber station, a node, a device, an onboard unit (OBU), and so on.

Each of the plurality of communication nodes 110-1, 110-2, 110-3, 120-1,120-2, 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may support longterm evolution (LTE) (or, long term evolution-advanced (LTE-A)) definedin a cellular communication standard (e.g., 3rd generation partnershipproject (3GPP) standard). Each of the plurality of base stations 110-1,110-2, 110-3, 120-1, and 120-2 may operate in different frequency bandsor same frequency band. Each of the plurality of base stations 110-1,110-2, 110-3, 120-1, and 120-2 may be connected to each other through anideal backhaul link or a non-ideal backhaul link and exchangeinformation each other through the ideal backhaul link or the non-idealbackhaul link. Each of the plurality of base stations 110-1, 110-2,110-3, 120-1, and 120-2 may be connected to a core network (non-shown)through the ideal backhaul link or the non-ideal backhaul link. Each ofthe plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 maytransmit a signal which is received from the core network to a specificUE 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 and may transmit asignal which is received from the specific UE 130-1, 130-2, 130-3,130-4, 130-5, and 130-6 to the core network.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and120-2 may support downlink transmission based on OFDMA and uplinktransmission based on SC-FDMA. In addition, each of the plurality ofbase stations 110-1, 110-2, 110-3, 120-1, and 120-2 may support multipleinput multiple output (MIMO) transmission (e.g., single user-multipleinput multiple output (SU-MIMO), multi user-multiple input multipleoutput (MU-MIMO), massive MIMO, and the like), coordinated multipoint(CoMP) transmission, carrier aggregation (CA) transmission, transmissionin an unlicensed band, device to device (D2D) communications (e.g.,proximity service (ProSe)), and so on. Here, each of the plurality ofUEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform operationscorresponding to or supported by the base station 110-1, 110-2, 110-3,120-1, and 120-2.

For example, the second base station 110-2 may transmit a signal to theUE4 130-4 based on a SU-MIMO manner, and the UE4 130-4 may receive thesignal from the second base station 110-2 based on the SU-MIMO manner.Alternatively, the second base station 110-2 may transmit a signal tothe UE4 130-4 and the UE5 130-5 based on a MU-MIMO manner, and each ofthe UE4 130-4 and the UE5 130-5 may receive the signal from the secondbase station 110-2 based on the MU-MIMO manner. Each of the first basestation 110-1, the second base station 110-2, and the third base station110-3 may transmit a signal to the UE4 130-4 based on a CoMP manner, andthe UE4 130-4 may receive the signal from the first base station 110-1,the second base station 110-2, and the third base station 110-3 based onthe CoMP manner. Each of the plurality of the base stations 110-1,110-2, 110-3, 120-1, and 120-2 may transmit or receive a signal to orfrom the UE 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 belonging tocoverage of a corresponding base station based on a CA manner. Each ofthe first base station 110-1, the second base station 110-2, and thethird base station 110-3 may coordinate the D2D communications betweenthe UE4 130-4 and the UE5 130-5, and each of the UE4 130-4 and the UE5130-5 may perform the D2D communications which are coordinated by eachof the first base station 110-1, the second base station 110-2, and thethird base station 110-3.

Next, operation methods of the communication node in the wirelesscommunication network will be described. Although a method (e.g., signaltransmission or reception) performed by a first communication node willbe described, a second communication node corresponding thereto mayperform a method (e.g., signal reception or transmission) correspondingto the method performed by the first communication node. That is, whenan operation of the UE is described, the base station correspondingthereto may perform an operation corresponding to the operation of theUE. On the contrary, when an operation of the base station is described,the UE may perform an operation corresponding to an operation of thebase station.

Meanwhile, public safety communication technologies (e.g., disastercommunication technologies) based on a LTE/LTE-A system may include anearthquake and tsunami warning system (ETWS), a public warning system(PWS), the D2D communications (e.g., ProSe), a group communicationservice (GCSE), and so on. In the D2D communications and the GCSE,communications may be performed through radio channels between UEswithout passing through the base station. Functions of the D2Dcommunications may be divided to a function of commercial service, afunction of public safety, and so on. Scenarios of the D2Dcommunications may be as follows.

FIG. 3 is a concept diagram showing a first scenario of D2Dcommunications.

As shown in FIG. 3, each of a UE1 310 and a UE2 410 may be located outof coverage of a base station. For example, in the case of that amessage which will be transmitted to the UE2 410 exists, the UE1 310 maydirectly transmit the message to the UE2 410. In addition, the UE1 310may directly receive a message from the UE2 410. That is, each of theUE1 310 and the UE2 410 may transmit or receive the message based on theD2D communications. Resource allocation operations and control signalingoperations for the D2D communications may be basically performed basedon a distributed control manner.

FIG. 4 is a concept diagram showing a second scenario of D2Dcommunications.

As shown in FIG. 4, a UE1 310 may be located in coverage of a first basestation 300, and a UE2 410 may be located out of the coverage of thefirst base station 300. This case may be referred to as a “partialcoverage scenario.” For example, in the case of that a message whichwill be transmitted to the UE2 410 exists, the UE1 310 may directlytransmit the message to the UE2 410. In addition, the UE1 310 maydirectly receive a message from the UE2 410. That is, each of the UE1310 and the UE2 410 may transmit or receive the message based on the D2Dcommunications. The resource allocation operations and the controlsignaling operations for the D2D communications may be performed basedon the distributed control manner or a base station-based control manner(or, network-based control manner).

FIG. 5 is a concept diagram showing a third scenario of D2Dcommunications.

AS shown in FIG. 5, each of a UE1 310 and a UE2 410 may be located incoverage of a base station 300. For example, in the case of that amessage which will be transmitted to the UE2 410 exists, the UE1 310 maydirectly transmit the message to the UE2 410. In addition, the UE1 310may directly receive a message from the UE2 410. That is, each of theUE1 310 and the UE2 410 may transmit or receive the message based on theD2D communications. In the case of that the UEs 310 and 410 are locatedin the coverage of the first base station 300, the resource allocationoperations and the control signaling operations for the D2Dcommunications may be basically performed based on the basestation-based control manner (or, network-based control manner).

FIG. 6 is a concept diagram showing a fourth scenario of D2Dcommunications.

As shown in FIG. 6, a UE1 310 may be located in coverage of a first basestation 300, and a UE2 410 may be located in coverage of a second basestation 400. For example, in the case of that a message which will betransmitted to the UE2 410 exists, the UE1 310 may directly transmit themessage to the UE2 410. In addition, the UE1 310 may directly receive amessage from the UE2 410. That is, each of the UE1 310 and the UE2 410may transmit or receive the message based on the D2D communications. Inthe case of that the UEs 310 and 410 are located in the coverage of thebase stations 300 and 400, the resource allocation operations and thecontrol signaling operations for the D2D communications may be basicallyperformed based on the base station-based control manner (or,network-based control manner).

Meanwhile, the D2D communications may support a voice service in theLTE/LTE-A system and may support the voice service based on a singlequality of service (QoS). The UE supporting the D2D communications maytransmit data using a broadcast manner or a multicast manner instead ofa unicast manner. In the case of that the UE is located in the coverageof the base station, the D2D communications may be performed based on amode1. In the case of that the mode1 is used in the D2D communications,the base station may inform the UE of resource information (e.g., radioresource information) used for the D2D communications. For example, thebase station may allocate available resources (e.g., available radioresources) in a D2D communication resource pool for the UE. The UE mayperform the D2D communications using the resource (e.g., radioresources) allocated by the base station. Therefore, the D2Dcommunications may be performed without collisions between UEs.

In the case of that the UE is located out of the coverage of the basestation, the D2D communications may be performed based on a mode2. Inthe case of that the mode2 is used in the D2D communications, the UE mayrandomly select resources (e.g., radio resources) in the D2Dcommunication resource pool and perform the D2D communications using theselected resources (e.g., selected radio resources). Because theresources (e.g., radio resources) used for the D2D communications arerandomly selected, collisions between UEs may be occurred.

In the partial coverage scenario, the D2D communications may beperformed based on the mode1 or the mode2. Criterions for mode selectionmay be predefined. In this case, the UE may select the mode1 or the mode2 based on the predefined criterions and perform the D2D communicationsusing resources (e.g., radio resources) determined by the selected mode.

Direct communications may be performed based on the foregoing D2Dcommunication technologies. The direct communications may include theD2D communications, vehicle communications, machine type communication(MTC), machine to machine (M2M) based communications, internet of things(IoT) based communications, and so on. The vehicle communications may bevehicle to everything (V2X) communications. The V2X communications mayinclude vehicle to vehicle (V2V) communications, vehicle toinfrastructure (V2I) communications, vehicle to pedestrian (V2P)communications, in-vehicle networking (IVN) communications, and so on.Communications between OBUs, communications between the OBU and the RSU,and communications between RSUs may be performed based on the D2Dcommunication technologies. Discovery services, communication services,and so on between communication nodes may be provided based on thevehicle communications.

In embodiments which will be described below, the RSU may be thecommunication system, the base station, and the like, and the OBU may bethe UE, and the like. The UE may be a UE owned by a pedestrian, a UEowned by a user using a means of transportation (e.g., vehicle,motorcycle, bicycle, wheelchair, baby carriage, and the like), and soon. User information (e.g., information indicating whether an owner ofthe UE is a pedestrian, information indicating whether an owner of theUE is a user of the means of transportation, and so on) may beautomatically configured based on sensors (e.g., gyro sensor, and on thelike) embedded in the UE or measurement functions of the UE (e.g.,function which measures moving distance per unit of an hour, functionwhich measures change of received signal strength, and so on).Alternatively, the user information may be configured according to aninput of the user of the UE.

In the case of that the mode1 is used, the vehicle communications may beperformed using resources scheduled by the base station (e.g.,communication system, RSU). In the case of that the mode2 is used, thevehicle communications may be performed using resources which arerandomly selected in a vehicle communication resource pool configured bythe base station. The vehicle communication resource pool may beidentical to or different from the foregoing D2D communication resourcepool.

In the case of that the mode1 is used, the OBU (or, UE) may operate in aradio resource control (RRC) connected state, and the base station maycontrol management and allocation of resources. For example, the basestation may directly configure the mode (e.g., mode1 or mode2) of thevehicle communications. In the case of that data to be transmitted isgenerated, the OBU which operates in a RRC idle state may transit thestate of it. That is, the state of the OBU may be transited from the RRCidle state to the RRC connected state. The OBU which operates in the RRCconnected state may request allocation of resources for the vehiclecommunications to the base station. The OBU which operates in the RRCconnected state may transmit a buffer status report (BSR) to the basestation, ifneeded. In the case of that the allocation of resources forthe vehicle communications is requested form the OBU, the base stationmay allocate available resources in the vehicle communication resourcepool for the OBU. The OBU may transmit data using resources allocated bythe base station. In addition, the base station may allocate resourcesfor the OBU which operates in the RRC idle state based on asemi-persistence scheduling (SPS) manner. In this case, the OBU whichoperates in the RRC idle state may transmit data using resourcesallocated by the base station without collisions.

In the case of that the mode2 is used, regardless of the state (e.g.,RRC connected state or RRC idle state) of the OBU (or, UE), the OBU mayrandomly select resources in the vehicle communication resource poolconfigured by the base station and transmit data using the selectedresources. Meanwhile, the OBU may receive a synchronization signal fromother communication node (e.g., base station, RSU, OBU, UE, and so on)and transmit data using resources which are selected in the vehiclecommunication resource pool after adjusting synchronization of it basedon the received synchronization signal. The synchronization signal maybe transmitted, from an arbitrary communication node (e.g., basestation, RSU, OBU, UE, and so on), through resources configured fortransmission of the synchronization signal in the broadcast manner. Inthe case of that the synchronization signal is not detected, the OBU maytransmit the synchronization signal of itself. That is, the OBU mayoperate in a synchronization source.

In the below, a manner in which resources for the direct communications(e.g., D2D communications, vehicle communications, and so on) areallocated by the base station may be referred as to a “mode1 manner.”The resources which are allocated based on the mode1 manner may bereferred to as “mode1 resources.” A manner in which resources for thedirect communications (e.g., D2D communications, vehicle communications,and so on) are randomly selected by the OBU in the preconfigured vehiclecommunication resource pool may be referred to as a “mode2 manner.” Theresources which are selected based on the mode2 manner may be referredto as “mode2 resources.”

Meanwhile, a message which is periodically generated in the vehiclecommunications (hereafter, “periodic message”) may be transmitted usingthe mode1 resources regardless of the state (e.g., RRC connected stateor RRC idle state) of the OBU. A message which is generated according tooccurrence of a specific event (hereafter, “aperiodic message”) may betransmitted using the mode2 resources. The aperiodic message may betransmitted using the mode1 resources according to attributes ofrequired reliability, service coverage, latency, and so on.

The OBU may include an access stratum (AS) layer block supportingfunctions of a protocol layer for radio access (e.g., AS layer) and anon-access stratum (NAS) layer block supporting functions of a higherlayer (e.g., NAS layer or application layer). The AS layer may be aphysical layer (e.g., layer1), a medium access control (MAC) layer(e.g., layer2), or a RRC layer.

The OBU may cancel or omit the transmission of the periodic message. Forexample, in a first case of that radio resources for the transmission ofthe periodic message are not allocated, a second case of that radioresources for the transmission of the periodic message are not selected,or a third case of that an instruction (e.g., predefined criterion) ofthe higher layer which requests cancellation or omission thetransmission of the periodic message exits, the transmission of theperiodic message may be canceled or omitted. In the case of that thetransmission of the periodic message is canceled, omitted, or failed byother reasons, the OBU may transmit the periodic message in an aperiodicmanner. Alternatively, the OBU may transmit an updated periodic messagein a next transmission period (or, next transmission time).

Concretely, the AS layer block may obtain the periodic message from theNAS layer block and transmit the periodic message according to apreconfigured period. In the case of that the periodic message is nottransmitted, the AS layer block (e.g., physical layer block, MAC layerblock, or RRC layer block included in the AS layer block) may transmit asignaling parameter (or, primitive message between layer blocks includedin the OBU) or a differently defined control message, each of themindicates the transmission failure (or, transmission cancellation,transmission omission) of the periodic message, to the NAS layer block(e.g., block supporting control functions). In addition, reasons of thetransmission failure (or, transmission cancellation, transmissionomission) of the periodic message may also be reported to the NAS layerblock.

The NAS layer block may identify the transmission failure (or,transmission cancellation, transmission omission) of the periodicmessage by receiving the signaling parameter or the control message fromthe AS layer block. Alternatively, the NAS layer block may identify thetransmission failure (or, transmission cancellation, transmissionomission) of the periodic message based on other methods. In this case,the NAS layer block may instruct (e.g., trigger) the AS layer block totransmit the periodic message in the aperiodic manner. Alternatively,the NAS layer block may instruct (e.g., trigger) the AS layer block totransmit the updated periodic message in the next transmission period(or, next transmission time). Alternatively, the NAS layer block mayinstruct (e.g., trigger) the AS layer block to omit the transmission ofthe periodic message.

Meanwhile, the NAS layer block may adjust occurrence frequency (or,transmission period) of the periodic message. In addition, the NAS layerblock may maintain and manage updated latest information and control atransmission of the updated latest information in the next transmissionperiod (or, next transmission time). The NAS layer block may transmitthe occurrence frequency information (or, transmission periodinformation) of the periodic message and the control information relatedto maintenance/management/transmission of the updated latest informationto the AS layer block through a signaling parameter (or, primitivemessage between layer blocks included in the OBU) or a differentlydefined control message.

The NAS layer block may adjust the occurrence frequency (or,transmission period) of the periodic message based on pre-obtained amovement speed of the OBU (or, UE), a radio channel environment, reasonsof transmission failure (or, transmission cancellation, transmissionomission) of the periodic message, and so on. Alternatively, the NASlayer block may transmit, to the AS layer block, a signaling parameter(or, primitive message between layer blocks included in the OBU) or adifferently defined control message each of them requests a report ofthe movement speed of the OBU, the radio channel environment, thereasons of transmission failure (or, transmission cancellation,transmission omission) of the periodic message, and so on. In addition,the NAS layer block may adjust the occurrence frequency (or,transmission period) of the periodic message based on the movement speedof the OBU, the radio channel environment, the reasons of transmissionfailure (or, transmission cancellation, transmission omission) of theperiodic message, and so on which are reported from the AS layer block.

The AS layer block may obtain the occurrence frequency information (or,transmission period information) of the periodic message and the controlinformation related to maintenance/management/transmission of theupdated latest information from the NAS layer block. The AS layer blockmay transmit the periodic message according to the occurrence frequency(or, transmission period). The AS layer block maymaintain/manage/transmit the updated latest information based on thecontrol information. The AS layer block may transmit a transmissionresult of the periodic message and a maintenance/management/transmissionresult of the updated latest information to the NAS layer block. Inaddition, according to a request of the NAS layer block, the AS layerblock may report the movement speed of the OBU, the radio channelenvironment, the reasons of transmission failure (or, transmissioncancellation, transmission omission) of the periodic message, and so onto the NAS layer block.

Meanwhile, the foregoing adjustment operations of the occurrencefrequency (or, transmission period) of the periodic message andoperations related to maintenance/management/transmission of the updatedlatest information may be performed in the RRC layer block belonging tothe AS layer block instead of the NAS layer block. In this case, the NASlayer block may transmit control information related to adjustment ofthe occurrence frequency (or, transmission period) of the periodicmessage and control information related tomaintenance/management/transmission of the updated latest information tothe RRC layer block. The RRC layer block may adjust the occurrencefrequency (or, transmission period) of the periodic message using thecontrol information obtained from the NAS layer block and perform theoperations related to maintenance/management/transmission of the updatedlatest information. For example, the RRC layer block may transmit, tothe MAC layer block and the physical layer block, a signaling parameter(or, primitive message between layer blocks included in the OBU) or adifferently defined control message each of them requests to performoperations based on the adjusted occurrence frequency (or, adjustedtransmission period) of the periodic message. In addition, the RRC layerblock may transmit, to the MAC layer block and the physical layer block,a signaling parameter (or, primitive message between layer blocksincluded in the OBU) or a differently defined control message each ofthem requests to perform operations related tomaintenance/management/transmission of the updated latest information.In the case of that the signaling parameter (or, primitive messagebetween layer blocks included in the OBU) or the differently definedcontrol message is received from the RRC layer block, each of the MAClayer block and the physical layer block may adjust the occurrencefrequency (or, transmission period) of the periodic message and performthe operations related to maintenance/management/transmission of theupdated latest information based on the request of the RRC layer block.

Meanwhile, adjustment conditions of the occurrence frequency (or,transmission period) of the periodic message, conditions of transmissioncancellation (or, transmission omission) of the periodic message, and soon may be predefined based on a control massage of the NAS layer or aRRC control message (e.g., control information of the RRC layer). In thecase of that a current state is satisfied with the predefinedconditions, the AS layer block (e.g., RRC layer block, MAC layer block,physical layer block) may adjust the occurrence frequency (or,transmission period) of the periodic message and cancel (or, omit) thetransmission of the periodic message. In this case, the AS layer blockmay report an adjustment result of the occurrence frequency (or,transmission period) of the periodic message and a result of thetransmission cancellation (or, transmission omission) of the periodicmessage to the NAS layer block.

Next, transmission methods of the periodic message performed in thecommunication node (e.g., OBU, UE) will be described. In a first case ofthat the mode1 resources are not allocated, a second case of that themode2 resources are not selected, or a third case of that thetransmission of the periodic message is failed (or, canceled, omitted),following transmission methods may be used.

FIG. 7 is a flow chart showing a method for transmitting a periodicmessage performed in a communication node.

As shown in FIG. 7, an OBU (or, UE) may compare a transmission delaytime of the periodic message with a predefined transmission delay time(alternatively, the OBU (or, UE), or may compare the number oftransmission failures of the periodic message with the predefined numberof transmission failures) (S700). Each of the predefined transmissiondelay time and the predefined number of transmission failures may beconfigured based on a priority, an attribute, and so on of the periodicmessage. The OBU may acquire the predefined transmission delay time andthe predefined number of transmission failures through systeminformation (or, differently defined control message).

In the case of that the transmission delay time of the periodic messageis equal to or more than the predefined transmission delay time (or, thenumber of transmission failures of the periodic message is equal to ormore than the predefined number of transmission failures), an aperiodictransmission may be triggered. In the case of that the aperiodictransmission is triggered, the OBU may configure resources for theaperiodic transmission (S710). For example, the OBU may obtain mode1resources allocated by the base station. The mode1 resources may beallocated based on the foregoing mode1 manner. In addition, the OBU mayreport latest information, the transmission delay time, the number oftransmission failures, reasons of transmission failure, and so on of theperiodic message through an allocation procedure of the mode1 resources.

Alternatively, the OBU may select mode2 resources. The mode2 resourcesmay be selected based on the foregoing mode2 manner. In addition, theOBU may report the latest information, the transmission delay time, thenumber of transmission failures, reasons of transmission failure, and soon of the periodic messages through a selection procedure of the mode2resources. In addition, the OBU may obtain uplink resources allocated bythe base station. For example, the OBU may obtain the uplink resourcesby performing a requesting procedure of the uplink resources (e.g.,requesting procedure of scheduling) or an access procedure.

The OBU may determine whether the mode1 resources or the mode2 resourcesare available (S720). The OBU may transmit the periodic message usingthe mode1 resources when the mode1 resources are available(alternatively, the OBU may transmit the periodic message using themode2 resources when the mode2 resources are available) (S730). On theother hand, in the case of that both the mode1 resources and the mode2resources are unavailable, the periodic message may be transmitted viathe base station (S740). For example, the OBU may report the latestinformation, the transmission delay time, the number of transmissionfailures, reasons of transmission failure, and so on of the periodicmessage to the base station using the uplink resources. In the case ofthat the latest information, and so on of the periodic message isreceived from the OBU, the base station may transmit the periodicmessage including the latest information to other communication node(e.g., OBU, UE, RSU, base station). In this case, the base station maytransmit the periodic message through downlink resources in thebroadcast manner, multicast manner, or unicast manner. Alternatively,the base station may transmit the periodic message using PC5 interfacefor the vehicle communications.

FIG. 8 is a concept diagram showing embodiments of a vehiclecommunication network.

As shown in FIG. 8, a mobility management entity 1/gateway 1 (MME1/GW1)811, a MME2/GW2 812, a base station1 821, a base station2 822, a RSU1831, a RSU2 832, a UE1 841, a UE2 842, an OBU1 851, an OBU2 852, and soon may support the direct communications (e.g., D2D communications,vehicle communications). Each of the base station1 821 and the basestation2 822 may be connected to the MME1/GW1 811, the MME2/GW2, and soon through S1 interface. Each of the base station1 821 and the basestation2 822 may transmit or receive control information to or from theMME1/GW1 811, the MME2/GW2, and so on through a control plane and maytransmit or receive data to or from the MME1/GW1 811, the MME2/GW2, andso on through a data plane. The base station1 821 may be connected tothe base station2 822 through X2 interface.

The RSU1 831 supporting base station-functions may be connected to thebase station1 821 through X2 interface and the MME1/GW1 811 through S1interface. The RSU1 831 may perform transmission and receptionoperations of control information/data through X2 interface and S1interface. Here, S1 interface may be a logical interface, and the RSU1831 may be physically connected to the MME1/GW1 811 via the basestation1 821. Alternatively, the RSU1 831 supporting relay-functions(e.g., L3/L2 relay-functions) may be connected to the base station1 821through Un interface and may perform the transmission and receptionoperations of the control information/data through Un interface.Alternatively, the RSU1 831 supporting UE-functions (or, OBU-functions)may be connected to the base station1 821 through Uu interface and mayperform the transmission and reception operations of the controlinformation/data through Uu interface.

The RSU2 832 supporting the relay-functions (e.g., L3/L2relay-functions) may be connected to the base station2 822 through Uninterface and may perform the transmission and reception operations ofthe control information/data through Un interface. Alternatively, theRSU2 832 supporting the UE-functions (or, OBU-functions) may beconnected to the base station2 822 through Uu interface and may performthe transmission and reception operations of the controlinformation/data through Uu interface. The RSU1 831 may be connected tothe RSU2 832 through PC5 interface or Uu interface. The transmission andreception operations of the control information/data between the RSU1831 and the RSU2 832 may be performed through PC5 interface or Uuinterface.

The UE1 841 may be connected to the base station1 821 through Uuinterface and the OBU1 851 through PC5 interface. The UE1 841 mayperform the transmission and reception operations of the controlinformation/data through Uu interface and PC5 interface. The UE2 842 maybe connected to the base station2 822 through Uu interface and the OBU2852 through PC5 interface. The UE2 842 may perform the transmission andreception operations of the control information/data through Uuinterface and PC5 interface.

The OBU1 851 may be connected to the RSU 831 supporting the basestation-functions (or, relay-functions) through Uu interface, the UE1841 through PC5 interface, and the OBU2 852 through PC5 interface. TheOBU1 851 may perform the transmission and reception operations of thecontrol information/data through Uu interface and PC5 interface. TheOBU2 852 may be connected to the base station2 822 through Uu interface,the RSU2 832 supporting the UE-functions (or, OBU-functions) through PC5interface, the UE2 842 through PC5 interface, and the OBU1 851 throughPC5 interface. The OBU2 852 may perform the transmission and receptionoperations of the control information/data through Uu interface and PC5interface.

Here, PC5 interface may be PC5 interface for the D2D communications inthe LTE/LTE-A system or radio interface for the direct communications(e.g., PC5 interface for the vehicle communications) betweencommunication nodes (e.g., RSU, OBU, UE, and so on) in a vehiclecommunication network.

FIG. 9 is a concept diagram showing deployment scenarios of a cellularcommunication network.

As shown in FIG. 9, a base station may manage a plurality of cells(e.g., three cells). Each of the plurality of cells may be operated bysame operator or different operators. In addition, the cellularcommunication network may be divided to a plurality of zones. Theplurality of cells and the base station may be located in each zone.Alternatively, the base station may not be located in each zone. Thezone may be identical to a zone of the vehicle communication networkwhich will be described below.

FIG. 10 is a concept diagram showing deployment scenarios of a vehiclecommunication network.

As shown in FIG. 10, the vehicle communication network may include abase station, a RSU, an OBU, a UE, and so on. The RSU may be located ina traffic signal lamp, a traffic sign, a structure on a road, astructure which is adjacent to the road (e.g., streetlight, telegraphpole, roadside tree, and the like), a building which is adjacent to theroad, a centerline of the road, and so on. The RSU may perform the basestation-functions, the relay-functions, or the UE-functions (or,OBU-functions). The OBU may be located in the means of transportation.The UE may be a UE owned by a pedestrian, a UE owned by a user using themeans of transportation.

The zone may include at least one RSU, at least one OBU, at least oneUE, and so on. The zone may be configured in consideration of a movementspeed, density, a movement path, and so on of a vehicle (or, OBU, UE).For performing efficiently the direct communications (e.g., D2Dcommunications, vehicle communications, and so on) in a single zone,frequency information (e.g., bandwidth, center frequency, and so on),configuration information of the physical layer (e.g., configurationinformation of synchronization signal, reference signal, pilot signal,and so on), configuration/deployment information of resource elements(or, resource blocks) in a radio frame (or, subframe),configuration/mapping information of a direct communication resourcepool, and so on may be exchanged in cells. Therefore, cells in thesingle zone may be operated identically. Here, the direct communicationresource pool may be a D2D communication resource pool, a vehiclecommunication resource pool, and so on. In addition, the directcommunication resource pool may include a resource pool for discoveryoperations, a resource pool for data communications, and so on.

Though an operator of each cell in the single zone or neighboring zonesis different each other (e.g., inter-public land mobile network (PLMN)),an operator to which each OBU (or, UE) subscribes is different eachother, or a vendor of each vehicle is different each other, theforegoing information (e.g., frequency information, configurationinformation of the physical layer, configuration/deployment informationof the resource elements (or, resource blocks) in the radio frame (or,subframe), configuration/mapping information of the direct communicationresource pool, and so on) may be used identically so that the vehiclecommunications are available. In addition, the transmission andreception operations of the control information/data may be performedbased on same access procedure.

Meanwhile, the resources for the direct communications in the vehiclecommunication network (e.g., vehicle communication resource pool) may beconfigured based on the foregoing mode1 manner or mode2 manner. In thevehicle communication network, an edge node (e.g., base station, cell,access point, RSU, and so on) may configure the vehicle communicationresource pool based on at least one following parameter. Here, thevehicle communication resource pool for respective vehicles (or, OBUs,UEs) or respective zones may be configured.

-   -   Road-related parameter (e.g., width of roadway, the number of        roadways, the number of intersections, type of intersection,        type of road (e.g., city street, trunk road, side road,        motorway, highway, and so on), state of road (e.g., freezing,        inundation, and so on), accident situation, and so on)    -   Vehicle-related parameter (e.g., the number of vehicles (or,        OBUs, UEs), density of vehicle (or, OBU, UE) (e.g., the number        of vehicles (or, OBUs, UEs) per unit area), a movement speed        (e.g., average movement speed) of vehicle (or, OBU, UE), a        movement path of vehicle (or, OBU, UE), and so on)    -   Service-related parameter (e.g., coverage of respective services        (e.g., effective range of respective services), transmission        reliability, and so on)    -   Message-related parameter (e.g., transmission manner of message        (e.g., periodic manner, aperiodic manner (or, event manner), and        so on), characteristic of data included in message (e.g.,        priority, size, type, and so on of data), and so on)    -   Operating time-related parameter (e.g., office-going hour,        closing hour, weekday, weekend, and so on)

For example, in the case of that it is anticipated that a large numberof vehicles (or, OBUs, UEs) exist based on the road-related parameter,the vehicle communication resource pool may be configured to includerelatively many resources. On the contrary, in the case of that it isanticipated that a small number of vehicles (or, OBUs, UEs) exist basedon the road-related parameter, the vehicle communication resource poolmay be configured to include relatively few resources.

In the case of that it is anticipated that a large number of vehicles(or, OBUs, UEs) exist based on the vehicle-related parameter, thevehicle communication resource pool may be configured to includerelatively many resources. On the contrary, in the case of that it isanticipated that a small number of vehicles (or, OBUs, UEs) exist basedon the vehicle-related parameter, the vehicle communication resourcepool may be configured to include relatively few resources. In addition,in the case of that a speed of the vehicle is equal to or less thanpredefined threshold (or, density of vehicle is more than predefinedthreshold), the vehicle communication resource pool may be configured toinclude relatively many resources. On the contrary, in the case of thata speed of vehicle is more than predefined threshold (or, density ofvehicle is equal to or less than predefined threshold), the vehiclecommunication resource pool may be configured to include relatively fewresources.

Here, the OBU (or, UE) may report the vehicle-related parameter to thebase station (or, RSU). In addition, a server which is connected to theOBU may estimate the vehicle-related parameter based on informationobtained from a navigation system of the vehicle and report theestimated vehicle-related parameter to the base station. Alternatively,in the case of that sensors or image devices (e.g., closed circuittelevision (CCTV), camera, and the like) are installed in the basestation, the base station may estimate the vehicle-related parameterusing the sensors or the image devices.

In the case of that it is determined that a service has relatively broadcoverage based on the service-related parameter, the vehiclecommunication resource pool may be configured to include relatively manyresources. On the contrary, in the case of that it is determined that aservice has relatively narrow coverage based on the service-relatedparameter, the vehicle communication resource pool may be configured toinclude relatively few resources.

In the case of that it is determined that many data to be transmittedexist based on the message-related parameter, the vehicle communicationresource pool may be configured to include relatively many resources. Onthe contrary, in the case of that it is determined that few data to betransmitted exist based on the message-related parameter, the vehiclecommunication resource pool may be configured to include relatively fewresources.

In the case of that it is anticipated that a large number of vehicles(or, OBUs, UEs) exist based on the operating time-related parameter, thevehicle communication resource pool may be configured to includerelatively many resources. On the contrary, in the case of that it isanticipated that a small number of vehicles (or, OBUs, UEs) exist basedon the operating time-related parameter, the vehicle communicationresource pool may be configured to include relatively few resources.

In addition, the base station may configure the vehicle communicationresource pool so that reuse of resources is available. For example, thebase station may configure the vehicle communication resource pool sothat different resources are allocated to each of consecutive zones inorder to reduce interferences in the vehicle communications. The basestation may configure the vehicle communication resource pool so thatsame resources are allocated to separated zones (i.e., non-consecutivezones).

The base station may transmit the configuration information of thevehicle communication resource pool to the OBU through the systeminformation or a dedicated control message. The configurationinformation of the vehicle communication resource pool may include atleast one of system bandwidth, transmission bandwidth, frequencyresource information (e.g., subcarrier index, and the like), timeresource information (e.g., subframe index, slot index, symbol index,and the like), resource allocation period, information on use authorityof resources (e.g., priority), configuration information of channels inthe physical layer, a valid time of the configuration information of thevehicle communication resource pool, a valid service area (e.g., cellidentifier, tracking area identifier, zone identifier, and the like) ofthe configuration information of the vehicle communication resourcepool, and allocation manner (e.g., mode1 manner or mode2 manner) of thevehicle communication resource pool.

The OBU may receive the configuration information of the vehiclecommunication resource pool from the base station and identify resourcesused for the vehicle communications based on the vehicle communicationresource pool. Therefore, the OBU may perform the vehicle communicationsusing resources belonging to the vehicle communication resource pool.

Meanwhile, a modulation and coding scheme (MCS) may be configured by thebase station (or, RSU) or OBU (or, UE) in the vehicle communications.The base station may configure the MCS using at least one of theroad-related parameter, the vehicle-related parameter, theservice-related parameter, the message-related parameter, and theoperating time-related parameter. The base station may configure aspecific MCS index (e.g., specific MCS level) or an available MAC range.The MCS index (or, MCS range) may be configured per the vehicle (or,OBU, UE) or the zone. For example, in the case of that the MCS index(or, MCS range) is configured per the zone, the OBUs belonging to thezone may use same MCS index (or, MCS range).

The base station may transmit the configured MCS information (e.g., MCSindex, MCS range) to the OBU through the system information or thededicated control message. The OBU may receive the MCS information fromthe base station. In the case of that the MCS index is received, the OBUmay perform the vehicle communications using MCS indicated by the MCSindex. In the case of that the MCS range is received, the OBU may selectMCS in the MCS range and perform the vehicle communications using theselected MCS.

Meanwhile, a fixed MCS may be used in the base station and the OBU. Forexample, the fixed MCS may be used according to characteristics (e.g.,priority, size, type, and the like) of data included in a message.Alternatively, the fixed MCS for respective zones (or, roads) may beused. In the case of that the fixed MCS is used, control information(e.g., sidelink control (SC) information in the D2D communications basedon LTE/LTE-A) including scheduling information for resources used fortransmission of data to which the fixed MCS is applied may not betransmitted. For example, the periodic message which is transmitted inthe broadcast manner or a message including data whose size belongs topreconfigured range may be transmitted using the fixed MCS withoutadditional scheduling information. In particular, when resources for thevehicle communications are allocated in the SPS manner, the fixed MCSmay be effectively used. In addition, a message to which the fixed MCSis applied may be transmitted through resources except for resources inwhich a message to which MCS configured by the base station or the OBUis applied is transmitted.

Meanwhile, the OBU may configure the MCS using at least one of theroad-related parameter, the vehicle-related parameter, theservice-related parameter, the message-related parameter, and theoperating time-related parameter. Here, a predefined threshold used forcomparing each parameter (e.g., road-related parameter, vehicle-relatedparameter, service-related parameter, message-related parameter,operating time-related parameter, and so on) may be transmitted to theOBU through signaling by the base station or may be pre-stored in theOBU. Criterions (e.g., mapping relation between each parameter and theMCS) for determining MCS (e.g., high efficiency MCS, low efficiency MCS)may be transmitted to the OBU through signaling by the base station ormay be per-stored in the OBU.

For example, in the case of that a speed of the vehicle is equal to ormore than the predefined threshold (e.g., the speed of the vehicle is ahigh speed), the OBU may use the high efficiency MCS (e.g., high ordermodulation manner (e.g., 16 quadrature amplitude modulation (QAM), 64QAM, and so on) and high coding rate (e.g., 1/2, 2/3, 4/5, and so on)).In the case of that a speed of the vehicle is less than the predefinedthreshold (e.g., the speed of the vehicle is a low speed), the OBU mayuse the low efficiency MCS (e.g., low order modulation manner (e.g.,binary phase shift keying (BPSK), quadrature phase shift keying (QPSK),and so on) and low coding rate (e.g., 1/12, 1/6, 1/3, and so on)). Thepredefined threshold used for determining the speed of the vehicle (or,OBU, UE) may be transmitted to the OBU through signaling by the basestation or may be pre-stored in the OBU. The criterions (e.g., mappingrelation between the speed of the vehicle and the MCS) for determiningMCS (e.g., high efficiency MCS, low efficiency MCS) may be transmittedto the OBU through signaling by the base station or may be per-stored inthe OBU.

In addition, in the case of that density of the vehicle (or, OBU, UE)(or, a size of data) is equal to or more than the predefined threshold,the OBU may use the high efficiency MCS (e.g., high order modulationmanner (e.g., 16 QAM, 64 QAM, and so on) and high coding rate (e.g.,1/2, 2/3, 4/5, and so on)). In the case of that density of the vehicle(or, OBU, UE) (or, a size of data) is less than the predefinedthreshold, the OBU may use the low efficiency MCS (e.g., low ordermodulation manner (e.g., BPSK, QPSK, and so on) and low coding rate(e.g., 1/12, 1/6, 1/3, and so on)). The predefined threshold used fordetermining the density of the vehicle (or, a size of data) may betransmitted to the OBU through signaling by the base station or may bepre-stored in the OBU. The criterions (e.g., mapping relation betweenthe density of the vehicle (or, a size of data) and the MCS) fordetermining MCS (e.g., high efficiency MCS, low efficiency MCS) may betransmitted to the OBU through signaling by the base station or may beper-stored in the OBU.

In addition, in the case of that coverage of service (or, range ofservice) is equal to or more than the predefined threshold (e.g., 50meter (m) or 1 kilometer (km)), the OBU may use the low efficiency MCS(e.g., low order modulation manner (e.g., BPSK, QPSK, and so on) and lowcoding rate (e.g., 1/12, 1/6, 1/3, and so on)). In the case of thatcoverage of service (or, range of service) is less than the predefinedthreshold (e.g., 200 m or 300 m), the OBU may use the high efficiencyMCS (e.g., high order modulation manner (e.g., 16 QAM, 64 QAM, and soon) and high coding rate (e.g., 1/2, 2/3, 4/5, and so on)). Thepredefined threshold used for determining the coverage of service (or,range of service) may be transmitted to the OBU through signaling by thebase station or may be pre-stored in the OBU. The criterions (e.g.,mapping relation between the coverage of service (or, range of service)and the MCS) for determining MCS (e.g., high efficiency MCS, lowefficiency MCS) may be transmitted to the OBU through signaling by thebase station or may be per-stored in the OBU.

Next, methods for supporting self-driving in the vehicle communicationnetwork (e.g., vehicle communication network shown in FIG. 10) will bedescribed. The RSU supporting self-driving may be a RSU installed in atraffic signal lamp of an intersection (or, crosswalk), a RSUinteroperated with the traffic signal lamp of the intersection (or,crosswalk), or a RSU installed in a structure (or, building) which isadjacent to the road, and so on. In addition, the RSU may support thebase station-functions or the relay-functions. In this case, the RSU mayconfigure the direct communication resource pool and support connectionfunctions between an infrastructure network and the OBU.

The RSU may control the traffic signal (e.g., operation timing of thetraffic signal, stop of operation of a specific traffic signal) byexchanging information with a transportation control center (e.g.,intelligent transportation system (ITS), and the like) (or, withoutexchange of the information). The RSU may transmit or receive thecontrol information/data to or from the OBU using resources (e.g., radiointerface (e.g., Uu interface) between the base station and the UE) forthe direct communications (e.g., D2D communications, vehiclecommunications).

The RSU may obtain the vehicle-related parameter from the OBU orestimate the vehicle-related parameter using additional sensors, imagedevices, and so on. In addition, the RSU may obtain the vehicle-relatedparameter from other RSU which is located in or interoperated with thetraffic signal lamp of an adjacent intersection (or, crosswalk). The RSUmay control the traffic signal in consideration of the vehicle-relatedparameter.

The RSU may transmit a control message instructing deceleration, stop ofacceleration, or stop to the OBU before a stop signal of the trafficsignal lamp turns on (e.g., prior to predefined reference time). Inaddition, the RSU may transmit a control message indicating an operatingtime of the stop signal of the traffic signal lamp to the OBU. Here, theoperating time may be remaining duration until the stop signal turns onor an exact time at which the stop signal operates. In the case of thatthe control message related to the stop signal is received, the OBU maycontrol the vehicle to decelerate speed or to be stopped based on thespeed of the vehicle, a road situation (e.g., road-related parameter), adistance from a preceding vehicle, and so on. In particular, the vehiclesupporting self-driving may perform efficiently self-driving functionsbased on information obtained by the direct communications with the RSUinstead of information collected by sensors used for self-driving. Forexample, the RSU may enhance efficiency of the self-driving functions bytransmitting a control signal informing operations (or, end ofoperations) of the traffic signal lamp indicating start, stop,light-turn, right-turn, and so on and operations (or, end of operations)of a traffic signal lamp installed in a crosswalk for a pedestrian tothe OBU.

The RSU may obtain user information (i.e., user information of the UE)from the UE located on the road (e.g., sidewalk) using resources (e.g.,radio interface (e.g., Uu interface) between the base station and theUE) for the direct communications (e.g., D2D communications, vehiclecommunications) and transmit the obtained information to the OBU locatedon the road. The user information may be safety-related information(e.g., information for preventing vehicle accidents). For example, theuser information may include a location, a speed, a type (e.g., disabledperson, child, and so on), a walking assist device, the means oftransportation (e.g., bicycle) of the user (e.g., pedestrian), and soon.

Alternatively, the RSU may obtain the user information using othermethods instead of the direct communications and transmit the obtaineduser information to the OBU located on the road. For example, the RSUmay obtain the user information based on image information obtained fromthe image devices (e.g., CCTV, camera, and the like). Alternatively, theRSU may obtain the user information through gaze communications (or,look and link communications). Here, the gaze communications (or, lookand link communications) may be point-to-point direct communications inwhich information is obtained from a counterpart communication node bytransmitting radio wave (or, beam) having strong straightness to thecounterpart communication node. According to the gaze communications(or, look and link communications), communications with the counterpartcommunication node may be performed though identifier information (e.g.,phone number, source ID, destination ID, and so on) of the counterpartcommunication node is unknown.

The RSU may obtain vehicle information (i.e., information of vehicle inwhich the OBU is installed) from the OBU located on the road andtransmit the obtained vehicle information to the UE located on the road(e.g., sidewalk). According to the foregoing operations, the vehicleaccidents may be prevented. Here, the vehicle information may be thespeed, the movement path, and the type of the vehicle.

Meanwhile, in the case of that it is identified that the pedestrianexists by the additional sensors or the image devices (e.g., CCTV,camera, and the like), the RSU may transmit the identifiedpedestrian-related information (e.g., user information) to the OBU usingresources for the direct communications in the broadcast manner.Alternatively, in the case of that it is identified that the pedestrianexists, the RSU may request a transmission of the user information tothe UE of the pedestrian and obtain the user information in response tothe request from the UE. Regardless of the request of the transmissionof the user information, the UE may transmit the user information to theRSU when it is identified that the RSU exists. The RSU may generate analarm message for preventing the vehicle accidents in consideration ofthe obtained user information and transmit the generated alarm messageto the OBU located on the road.

Meanwhile, the foregoing user information (or, vehicle information) maybe transmitted to a RSU which performs monitoring operations on theroad-related parameter and a RSU which supports the relay-functions outof coverage of the communication network.

Next, communication methods performed by the communication node in thevehicle communication network will be described.

FIG. 11 is a sequence chart showing embodiments of a communicationmethod performed by a communication node in a vehicle communicationnetwork.

As shown in FIG. 11, each of a base station1 and a base station2 may bethe base station 821, 822 or the RSU 831, 832 shown in FIG. 8. Each ofan OBU1 and an OBU2 may be the UE 841, 842 or the OBU 851, 852 shown inFIG. 8. For example, the transmission and reception operations of thecontrol information/data between the base station and the OBU may beperformed through Uu interface. The transmission and receptionoperations of the control information/data between OBUs may be performedthrough PC5 interface. Each of the base station1, the base station2, theOBU1, and the OBU2 may be identical or similar to a structure of thecommunication node 200 shown in FIG. 2. An operator of the base station1may be identical to or different from an operator of the base station2.An operator to which the OBU1 subscribes may be identical to ordifferent from an operator to which the OBU2 subscribes.

Meanwhile, the base stations may pre-negotiate the direct communicationresource pool so that the direct communications are performed regardlessof the state of OBUs (e.g., RRC connected state, RRC idle state). Theconfiguration information of the direct communication resource pool mayinclude the system bandwidth, the center frequency, the frequencyresource information, the time resource information, the resource period(or, resource interval), and so on. The direct communication resourcepool may be divided to a transmission resource pool, a receptionresource pool, and so on. In addition, the direct communication resourcepool may be divided to a resource pool for discovery operations, aresource pool for data communications, and so on.

An operation for connection (e.g., bearer) configuration (or,establishment) between the base station1 and the OBU1 may be performed(S1100). In the case of that the operation of the connectionconfiguration (or, establishment) is completed, the OBU1 may operate inthe RRC connected state. In the step S1100, the base station1 mayallocate resources of the direct communication for the OBU1 based on themode1 manner. For example, the base station1 may select the resources ofthe direct communication in the direct communication resource pool(e.g., direct communication resource pool which is pre-negotiatedbetween the base stations) and transmit the selected resources to theOBU1. The OBU1 may obtain resource information from the base station1and identify the resources of the direct communications based on theobtained resource information.

The OBU2 may operate in the RRC idle state without connectionconfiguration (or, establishment) with the base station2. For example,the OBU2 may operate in a camping state in which the OBU2 is camped inthe base station2. The resources of the direct communications for theOBU2 may be configured based on the mode2 manner. For example, the basestation2 may transmit the system information including the configurationinformation of the direct communication resource pool (e.g., directcommunication resource pool which is pre-negotiated between the basestations) (S1101). The OBU2 may acquire the system information from thebase station2 and identify the configuration information of the directcommunication resource pool from the system information. Here, it isdescribed that the step S1101 is performed after the step S1100,however, performing order of the step S1101 may not be limited thereto.For example, the step S1101 and the step S1100 may be performedsimultaneously, or the step S1101 may be performed prior to the stepS1100.

After that, the OBU1 may transmit the control information (or, data) tothe OBU2 using the direct communications (S1102). The transmission andreception operations of the control information (or, data) may beperformed though the state of the OBU1 (e.g., RRC connected state) isdifferent from the state of the OBU2 (e.g., RRC idle state). Forexample, the OBU1 may transmit scheduling information for the controlinformation (or, data) using an additional control channel (e.g.,resources used for transmitting the scheduling information) of thephysical layer for the direct communications. The scheduling informationmay include resource allocation information (e.g., frequency resourceinformation, time resource information), MCS information, and so on.Here, the MCS information may be configured based on at least one of theroad-related parameter, the vehicle-related parameter, theservice-related parameter, the message-related parameter, and theoperating time-related parameter.

After transmitting the scheduling information, the OBU1 may transmit thecontrol information (or, data) to which MCS indicated by the schedulinginformation is applied through resources indicated by the schedulinginformation. Meanwhile, the OBU2 may obtain the scheduling informationfrom the OBU1 by monitoring the resources belonging to the directcommunication resource pool. The OBU2 may obtain the control information(or, data) through the resources indicated by the scheduling informationand perform demodulation/decoding operations on the control information(or, data) based on the MCS indicated by the scheduling information.

The OBU2 may randomly select resources in the direct communicationresource pool which is obtained in the step S1101 and transmit thecontrol information (or, data) to the OBU1 using the selected resources(S1103). The OBU1 may identify the configuration information of thedirect communication resource pool (e.g., direct communication resourcepool which is pre-negotiated between the base stations) based on thesystem information or the control message each of them is transmittedfrom the base station1. The OBU1 may receive the control information(or, data) from the OBU2 by performing monitoring operations on theresources belonging to the identified direct communication resourcepool. In addition, the OBU1 may obtain the scheduling information froman adjacent communication node and receive the control information (or,data) from the OBU2 through the resources indicated by the schedulinginformation.

Meanwhile, in the case of that resources used for transmitting thecontrol information (or, data) do not exist (e.g., in the case of thatthe resources which are allocated in the step S1100 are unavailable),the OBU1 may request resource allocation to the base station1 (e.g.,OBU1 may transmit a control message requesting the resource allocationto the base station1) (S1104). For example, the OBU1 may request theresource allocation to the base station1 based on a random accessprocedure, a requesting procedure for scheduling a physical uplinkcontrol channel (PUCCH), or the BSR procedure. Additional resources(e.g., resources which are allocated based on the random accessprocedure, resources which are allocated based on the BSR procedure, andso on) for the OBU1 may be configured so that interferences which areoccurred to other communication node serviced by the base station1 areminimized. In particular, an additional PUCCH for the directcommunications may be configured.

In the case of that the request of the resource allocation is receivedfrom the OBU1, the base station1 may allocate the resources of thedirect communications (S1105). For example, the base station1 may selectthe resources of the direct communications in the direct communicationresource pool (e.g., direct communication resource pool which ispre-negotiated between the base stations) and transmit the selectedresource information to the OBU1. The resources of the directcommunications which are allocated in the step S1105 may be differentfrom the resources of the direct communications which are allocated inthe step S1100. In the case of that the resources of the directcommunications are allocated, the OBU1 may transmit the controlinformation (or, data) to other communication node (e.g., OBU2) usingthe allocated resources (S1106). In the case of that the requestingprocedure (i.e., steps S1104 and S1105) for the resource allocation isnot performed, the OBU1 may randomly select resources in the directcommunication resource pool which is obtained from the systeminformation or the control message and transmit the control information(or, data) to other communication node (e.g., OBU2) using the selectedresources. The OBU2 may receive the control information (or, data) fromthe OBU1 by monitoring resources belonging to the direct communicationresource pool obtained in the step S1101.

Meanwhile, the OBU2 which operates in the RRC idle state may perform anoperation for connection establishment (or, configuration) with the basestation2, if necessary (S1107). In the case of that the operation forthe connection establishment (or, configuration) is completed, the OBU2may operate in the RRC connected state. In the step S1107, the basestation2 may allocate resources of the direct communication for the OBU2based on the mode1 manner. For example, the base station2 may select theresources of the direct communication in the direct communicationresource pool (e.g., direct communication resource pool which ispre-negotiated between the base stations) and transmit the selectedresource information to the OBU2. The OBU2 may obtain the resourceinformation from the base station2 and identify the resources of thedirect communications based on the obtained resource information. Afterthat, the OBU2 may transmit the control information (or, data) to theOBU1 using the resources allocated by the base station2 (S1108). TheOBU1 may receive the control information (or, data) from the OBU2 bymonitoring resources belonging to the direct communication resource poolwhich is obtained through the system information or the control message.

Meanwhile, in the case of that a direct communication service based onthe mode1 manner is ended, the OBU1 may transmit a message instructingan end of the direct communication service based on the mode1 manner tothe base station1 (S1109). In the case of that the message instructingthe end of the direct communication service based on the mode1 manner isreceived, the base station1 may perform a resource release operation ora connection release operation of the direct communications (S1110).When the resource release operation is performed, the base station1 mayrelease the resources which are configured for the direct communicationsof the OBU1. In this case, the OBU1 may not perform the directcommunication functions and operate in the RRC connection state. Whenthe connection release operation is performed, the base station1 mayrelease the resources which are configured for the direct communicationsof the OBU1 and the connection with the OBU1. In this case, the basestation1 may transmit a reconfiguration message informing connectionrelease to the OBU1. The reconfiguration message may include theconfiguration information of the direct communication resource pool(e.g., direct communication resource pool which is pre-negotiatedbetween the base stations). Here, the OBU1 may operate in the RRC idlestate and identify the configuration information of the directcommunication resource pool by receiving the reconfiguration message.

After that, in the case of that the control information (or, data) whichwill be transmitted based on the direct communication manner isgenerated, the OBU1 may randomly select resources in the directcommunication resource pool which is obtained through the systeminformation or the step S1110 and transmit the control information (or,data) to the OBU2 using the selected resources (S1111). The OBU2 mayreceive the control information (or, data) from the OBU1 by monitoringresources belonging to the direct communication resource pool which isobtained through the step S1101.

Meanwhile, in the case of that resources used for transmitting thecontrol information (or, data) do not exist (e.g., in the case of thatthe resources which are allocated in the step S1107 are unavailable),the OBU2 may request resource allocation to the base station1 (e.g.,OBU2 may transmit a control message requesting the resource allocationto the base station1) (S1112). Here, the step S1112 may be identical orsimilar to the foregoing step S1104. The OBU2 may obtain the resourcesof the direct communications in response to the request of the resourceallocation from the base station2 and transmit the control information(or, data) using the obtained resources.

The foregoing steps S1100 to S1112 may not be performed sequentially.Some steps (e.g., steps for the operation for the connectionestablishment (or, configuration) (i.e., S1100 and S1107), steps for theresource allocation request (i.e., S1104, S1105, and S1112), steps forthe transmission of the control information/data (i.e., S1102, S1103,S1106, S1108, and S1111), steps for the end of the direct communications(i.e., S1109 and S1110), and so on) may be performed optionally.

Next, in the vehicle communication network, communication methods basedon the gaze communications (or, image information) will be described.

FIG. 12 is a sequence chart showing embodiments of a communicationmethod based on gaze communications (or, look and link communications)in a vehicle communication network.

As shown in FIG. 12, the vehicle communication network may include apreceding vehicle, a following vehicle, and so on. Each of the precedingvehicle and the following vehicle may include the OBU 851, 852 or the UE841, 842 shown in FIG. 8. Each of the preceding vehicle and thefollowing vehicle may include the image devices. The following vehiclemay obtain images of the preceding vehicle using the image devices andestimate information of the preceding vehicle (e.g., a type and numberof the preceding vehicle, and so on) by analyzing the obtained images(S1200).

The following vehicle may transmit a message including the informationof the preceding vehicle, information of the following vehicle (e.g., atype and number of the following vehicle, and so on), an identifier ofthe following vehicle, and so on to the preceding vehicle (S1201). Inthis case, the following vehicle may transmit the message including theinformation of the preceding vehicle, the information of the followingvehicle, the identifier of the following vehicle, and so on to thepreceding vehicle using the direct communications or the gazecommunications (or, look and link communications). In the case of thatthe direct communications are used, the message may be transmitted inthe broadcast manner or the multicast manner. In the case of that thegaze communications (or, look and link communications) are used, themessage may be transmitted through the radio wave (or, beam) havingstrong straightness.

The preceding vehicle may receive the message from the following vehicleand identify the information of the preceding vehicle, the informationof the following vehicle, the identifier of the following vehicle, andso on included in the message. In the case of that a reliability of themessage (or, information included in the message) received from thefollowing vehicle is satisfied with a predefined criterion (or, ifnecessary), the preceding vehicle may transmit a message including anidentifier of the preceding vehicle to the following vehicle (S1202). Inthe case of that the steps S1201 and S1202 are performed, an operationrelated to join/out of a group, a report operation of a state of eachvehicle (e.g., abnormal state, and so on), and so on may be performed.

In the foregoing the steps S1200 to S1202, the preceding vehicle mayperform a role of the following vehicle, and the following vehicle mayperform a role of the preceding vehicle. For example, the steps S1200and S1201 may be performed by the preceding vehicle, and the step 1202may be performed by the following vehicle.

After that, the direct communications (e.g., point-to-point directcommunications) between the preceding vehicle and the following vehiclemay be performed (S1203). In the case of that the direct communicationsmay be performed, the operation related to join/out of the group, thereport operation of the state of each vehicle (e.g., abnormal state, andso on), and so on may be performed.

Meanwhile, for supporting the vehicle communications, the base station(or, RSU) may perform downlink transmission in the broadcast manner orthe multicast manner. For example, the base station may transmitinformation obtained from the OBU (or, UE) or the communication nodebelonging to the network (e.g., communication node belonging to thehigher layer) through broadcast resources (or, multicast resources) ofthe downlink. In the case of that the broadcast manner is used, the basestation may transmit the information obtained from the OBU or thenetwork through resources which are configured for transmission of amultimedia broadcast/multicast service (MBMS) single-frequency network(MBSFN) (hereafter, “MBSFN resources”).

The base station may transmit the control information/data related tothe vehicle communications using the MBSFN resources in the broadcastmanner according to a MBMS procedure. In this case, the base station mayconfigure an additional MBSFN subframe supporting the vehiclecommunications and transmit the control information/data related to thevehicle communications using the additional MBSFN subframe. In addition,the base station may transmit information obtained from the OBU to acommunication node (e.g., sever supporting the vehicle communications,MBMS coordination entity (MCE), and so on) belonging to the network.According to control of the communication node (e.g., sever supportingthe vehicle communications, MCE, and so on) belonging to the network,the base station may transmit the control information/data related tothe vehicle communications using the additional MBSFN subframe in thebroadcast manner.

Meanwhile, in the case of that the multicast manner is used, the basestation may transmit the control information of the physical layer usingan additional group scheduling identifier configured for the vehiclecommunications (e.g., V2X-radio network temporary identifier(V2X-RNTI)), and then transmit information using a physical downlinkshared channel (PDSCH) indicated (e.g., addressed) by the controlinformation of the physical layer. In particular, the base station mayperform simultaneously a transmission operation in which informationobtained from the OBU belonging to a specific group is transmitted to acommunication node (e.g., sever supporting the vehicle communications,MCE, and so on) belonging to the network and a transmission operation inwhich information obtained from the OBU belonging to the specific groupis transmitted to the specific group using a specific group schedulingidentifier in the multicast manner.

Here, in the case of that the control information/data related to thevehicle communications is received from the OBU through uplink resourcesor resources belonging to the vehicle communication resource pool, thebase station may identify a group to which the OBU transmitting thecontrol information/data related to the vehicle communications belongs.In this case, the base station may determine whether to transmit thecontrol information/data related to the vehicle communications to OBUsbelonging to the identified group regardless of the controlinformation/data related to the vehicle communications obtained from theOBU is transmitted to the communication node belonging to the network.For example, the base station may transmit the control information/datarelated to the vehicle communications to OBUs belonging to acorresponding group using a group identifier (e.g., destinationidentifier/address for the vehicle communications) or the groupscheduling identifier (e.g., V2X-RNTI). In this case, the controlinformation/data related to the vehicle communications may betransmitted through downlink resources in the multicast manner.

In the foregoing transmission procedure of the control information/datarelated to the vehicle communications, the OBU may transmit the controlinformation/data related to the vehicle communications using PC5interface or Uu interface, and the base station may transmit the controlinformation/data related to the vehicle communications using Uuinterface.

Meanwhile, in the LTE/LTE-A system, a message transmission may beperformed in unit of a physical resource block (PRB) for supporting theD2D communications, the vehicle communications, the MTC, the M2M basedcommunications, the IoT based communications, and so on. Here, themessage may include the control information and the data for the directcommunications, and so on. The message transmission based on the PRB maybe performed as follows.

FIG. 13 is a timing diagram showing embodiments of a method fortransmitting a message through PRB.

As shown in FIG. 13, a control channel may be a physical downlinkcontrol channel (PDCCH), a physical sidelink control channel (PSCCH),and so on, and a data channel may be the PDSCH, a physical sidelinkshared channel (PSSCH), and so on. The PRB may be configured accordingto a scheduling period. In addition, the PRB may be configured based ona frequency hopping manner. The base station (e.g., block, which isincluded in the base station, supporting scheduling functions) maygenerate scheduling information including PRB allocation information,MCS information, and so on. The base station may transmit the schedulinginformation through the control channel. The OBU may receive thescheduling information through the control channel from the base stationand transmit data to which MCS indicated by the scheduling informationis applied through the PRB indicated by the scheduling information.

Alternatively, the OBU may randomly select the PRB in the directcommunication resource pool which is pre-obtained from the base stationand transmit data through the selected PRB. In this case, the basestation may not transmit the scheduling information and may control theOBU to select randomly the PRB in the direct communication resourcepool. In addition, the base station may control the predefined OBU (or,UE, group) to select the PRB based on a scheduling pattern.

Next, a repetition transmission method of data in the directcommunications will be described. Here, the repetition transmission mayinclude retransmission, hybrid automatic repeat request (HARQ) basedtransmission, and so on. The data channel of the physical layer for thedirect communications may be the PUSCH and PSSCH of the LTE/LTE-Asystem, an additional data channel configured for the directcommunications, and so on. The control channel of the physical layer forthe direct communications may be the PDCCH, an enhanced PDCCH (EPDCCH),PUCCH, and PSCCH of the LTE/LTE-A system, an additional control channelconfigured for the direct communications, and so on.

For extending service coverage, enhancing transmission reliability, andso on in the direct communications, a message may be repeatedlytransmitted through PRB (e.g., PRB allocated by the base station, PRBselected by the OBU) in a transmission period (or, transmissionduration, transmission window), continuously or discretely. Here, themessage may include the control information and the data for the directcommunications, and so on. The transmission period may be a timeinterval which is configured in a time axis and may be additionallyconfigured for the direct communications. The transmission period may besignaled to the OBU through a control message. For example, thetransmission period may be a transmission period shown in FIG. 13.

The control information for the repetition transmission of data mayinclude the number of repeated transmissions, redundancy version (RV),MCS information, repetition transmission time, resource allocationinformation (e.g., system bandwidth, frequency resource information(e.g., subcarrier index, and the like), time resource information (e.g.,subframe index, slot index, symbol index, and the like), and so on. Thecontrol information for the repetition transmission may be transmittedin an explicit signaling manner or an implicit signaling manner.Alternatively, the control information for the repetition transmissionmay be configured by a communication node performing the repetitiontransmission of data. Here, the communication node may be the basestation, the UE, the RSU, the OBU, and so on.

A Repetition Transmission Method of Data Based on the Explicit SignalingManner

A transmitting communication node may transmit the control informationfor the repetition transmission to a receiving communication node.Alternatively, the control information for the repetition transmissionmay be preconfigured in the transmitting communication node and thereceiving communication node. Therefore, the transmitting communicationnode may perform the repetition transmission of data based on thecontrol information for the repetition transmission. The receivingcommunication node may receive data which is repeatedly transmittedbased on the control information for the repetition transmission andperform the demodulation/decoding operations on the received data. Inaddition, the receiving communication node may transmit a feedbackmessage (e.g., acknowledgement (ACK) message) indicating that the datais successfully received to the transmitting communication node.

A Repetition Transmission Method of Data Based on the Implicit SignalingManner

The number of repeated transmissions of data may be configured based oncapability of the communication node, a location of the communicationnode, the MCS information, the resource allocation information,attributes of service (e.g., attribute indicating whether to generatethe periodic message, attribute indicating whether to transmit divideddata, attribute indicating a transmission type of data, and so on),coverage (e.g., range) of service, a size of data, and so on. That is,mapping relation between the number of repeated transmissions and otherinformation may be preconfigured in the network, or may be transmittedto the communication node through an additional control signaling.

For example, the MCS index indicating 1 is mapped to the number ofrepeated transmissions indicating 2, the MCS index indicating 2 ismapped to the number of repeated transmissions indicating 4, and the MCSindex indicating 3 is mapped to the number of repeated transmissionsindicating 6. Therefore, the transmitting communication node may selectthe number of repeated transmissions mapped to the MCS index andtransmit repeatedly data according to the number of repeatedtransmissions. The receiving communication node may identify the numberof repeated transmissions mapped to the MCS index and receive data whichis repeatedly transmitted according to the number of repeatedtransmissions.

In addition, in the case of that the transmission manner of data may bedivided to a transmission manner based on a path (or, logic channel) ofa user plane and a transmission manner based on a path of a controlplane, the number of repeated transmissions mapped to the transmissionmanner based on the path of the user plane may be different from thenumber of repeated transmissions mapped to the transmission manner basedon the path of the control plane. In addition, the number of repeatedtransmissions may be differently configured according to whethertransmission of piggy back is performed.

In addition, mapping relation between a range of data size and thenumber of repeated transmissions may be preconfigured, and the number ofrepeated transmissions may be configured according to the range of datasize to which current data belongs.

A Repetition Transmission Method of Data Based on Configuration of theCommunication Node

A minimum number of repeated transmissions and a maximum number ofrepeated transmissions may be preconfigured in the network, or may betransmitted to the communication node through an additional controlsignaling. The transmitting communication node may configure the numberof repeated transmissions to as multiple of the minimum number ofrepeated transmissions. Here, the configured number of repeatedtransmissions may be equal to or less than the maximum number ofrepeated transmissions. In addition, the number of repeatedtransmissions may be variably configured according to the capability ofthe communication node, the location of the communication node, the MCSinformation, the resource allocation information, the attributes ofservice, the coverage of service, area of service, a size of data, andso on.

FIG. 14 is a timing diagram showing embodiments of a method forrepetition transmission of data.

As shown in FIG. 14, each of a transmitting communication node and areceiving communication node may be the foregoing base station, RSU, UE,OBU, and so on. T1 may indicate initial data, T2 may indicate secondrepeated data, T3 may indicate third repeated data, T4 may indicatefourth repeated data, T5 may indicate fifth repeated data, and T6 mayindicate sixth repeated data. Scheduling information of T1 (e.g.,resource allocation information, MCS information, and so on) may beconfigured by the communication node, or may be transmitted to thecommunication node through a differently defined control message. In thecase of that the scheduling information of T1 is determined, schedulinginformation of T2 (or, T3, T4, T5, T6, and so on) after T1 may beconfigured based on the scheduling information of T1.

The number of repeated transmissions of data may be determined based onthe foregoing manner. The mapping relation between the number ofrepeated transmissions and other information, the transmission period ofdata, an initial transmission time, a repetition transmission time, theminimum number of repeated transmissions, the maximum number of repeatedtransmissions, criterions (or, conditions, rules) for changing thenumber of repeated transmissions, a repetition transmission manner, thescheduling information, and so on may be referred to as a commonparameter. The common parameter may be configured in unit of a specificservice region (e.g., service area, cell, coverage, and the like), agroup of the communication node, or the communication node. The commonparameter may be signaled to the communication node through the systeminformation, the dedicated control message, a MAC control protocol dataunit (PDU), or a control field of the physical layer.

The transmitting communication node may repeatedly transmit dataaccording to the number of repeated transmissions in the transmissionperiod. The receiving communication node may receive data from thetransmitting communication node and perform the demodulation/decodingoperations on the received data by performing a soft combining operationbased on the minimum number of repeated transmissions in thetransmission period. Meanwhile, the receiving communication node mayperform the demodulation/decoding operations on data using repetitionreception techniques though the receiving communication node does notknow the number of repeated transmissions. Here, the soft combiningtechniques may include chase combining techniques, incrementalredundancy (IR) techniques, and so on. In addition, techniques (e.g.,transmission techniques of RV of cyclic redundancy check (CRC) or apattern of different parity bits) for combining repeated data (or, bit,symbol) may be used in order to enhance reception performance.

A Repetition Transmission Method of Data in a Case1 May be as Follows.

In the case1, the number of repeated transmissions may be 6. In thetransmission period, the transmitting communication node may repeatedlytransmit data (e.g., T1, T2, T3, T4, T5, and T6) in six times. Thereceiving communication node may receive the data (e.g., T1, T2, T3, T4,T5, and T6) from the transmitting communication node and perform themodulation/decoding operations on the receive data (e.g., T1, T2, T3,T4, T5, and T6) by performing the soft combining operation based on theminimum number of repeated transmissions.

In the case of that the minimum number of repeated transmissions is 2,the receiving communication node may perform the soft combiningoperation in unit of two data. The receiving communication node mayidentify a CRC by performing the soft combining operation on each of“T1, T2,” “T3, T4,” and “T5, T6.” In the case of that a CRC result oftwo data is “check good” (e.g., channel state is satisfied withpredefined criterion), a corresponding data may be transmitted to thehigher layer.

On the other hand, in the case of that the CRC result of two data is not“check good” (e.g., channel state is not satisfied with predefinedcriterion), the transmitting communication node may perform the softcombining operation on the result of the soft combining operation on“T1, T2” and the result of the soft combining operation on “T3, T4,” andmay perform the soft combining operation on the result of the softcombining operation on “T3, T4” and the result of the soft combiningoperation on “T5, T6.” In the case of that a CRC result of four data is“check good,” a corresponding data may be transmitted to the higherlayer.

On the other hand, in the case of that the CRC result of four data isnot “check good,” the transmitting communication node may perform thesoft combining operation on the result of the soft combining operationon “T1, T2,” the result of the soft combining operation on “T3, T4,” andthe result of the soft combining operation on “T5, T6.” In the case ofthat a CRC result of six data is “check good,” a corresponding data maybe transmitted to the higher layer. On the other hand, in the case ofthat the CRC result of six data is not “check good,” a messageindicating reception failure may be transmitted to the higher layer.

A Repetition Transmission Method of Data in a Case2 and a Case6 May beas Follows.

In each of the case2 and the case6, the number of repeated transmissionsmay be 4. In the transmission period, the transmitting communicationnode may repeatedly transmit data (e.g., T1, T2, T3, and T4) in fourtimes. The receiving communication node may receive the data (e.g., T1,T2, T3, and T4) from the transmitting communication node and perform themodulation/decoding operations on the receive data (e.g., T1, T2, T3,and T4) by performing the soft combining operation based on the minimumnumber of repeated transmissions.

In the case of that the minimum number of repeated transmissions is 2,the receiving communication node may perform the soft combiningoperation in unit of two data. The receiving communication node mayidentify a CRC by performing the soft combining operation on each of“T1, T2,” and “T3, T4.” In the case of that a CRC result of two data is“check good” (e.g., channel state is satisfied with predefinedcriterion), a corresponding data may be transmitted to the higher layer.

On the other hand, in the case of that the CRC result of two data is not“check good,” the transmitting communication node may perform the softcombining operation on the result of the soft combining operation on“T1, T2” and the result of the soft combining opration on “T3, T4.” Inthe case of that a CRC result of four data is “check good,” acorresponding data may be transmitted to the higher layer. On the otherhand, in the case of that the CRC result of four data is not “checkgood,” a message indicating reception failure may be transmitted to thehigher layer.

A Repetition Transmission Method of Data in a Case3, a Case4, and aCase5 May be as Follows.

In each of the case3, the case4, and the case5, the number of repeatedtransmissions may be 2. In the transmission period, the transmittingcommunication node may repeatedly transmit data (e.g., T1 and T2) in twotimes. The receiving communication node may receive the data (e.g., T1and T2) from the transmitting communication node and perform themodulation/decoding operations on the receive data (e.g., T1 and T2) byperforming the soft combining operation based on the minimum number ofrepeated transmissions. In the case of that the minimum number ofrepeated transmissions is 2, the receiving communication node mayperform the soft combining operation in unit of two data. The receivingcommunication node may identify a CRC by performing the soft combiningoperation on each of “T1, T2.” In the case of that a CRC result of twodata is “check good,” a corresponding data may be transmitted to thehigher layer. On the other hand, in the case of that the CRC result oftwo data is not “check good,” a message indicating reception failure maybe transmitted to the higher layer.

The embodiments of the present disclosure may be implemented as programinstructions executable by a variety of computers and recorded on acomputer readable medium. The computer readable medium may include aprogram instruction, a data file, a data structure, or a combinationthereof. The program instructions recorded on the computer readablemedium may be designed and configured specifically for the presentdisclosure or can be publicly known and available to those who areskilled in the field of computer software.

Examples of the computer readable medium may include a hardware devicesuch as ROM, RAM, and flash memory, which are specifically configured tostore and execute the program instructions. Examples of the programinstructions include machine codes made by, for example, a compiler, aswell as high-level language codes executable by a computer, using aninterpreter. The above exemplary hardware device can be configured tooperate as at least one software module in order to perform theembodiments of the present disclosure, and vice versa.

While the embodiments of the present disclosure and their advantageshave been described in detail, it should be understood that variouschanges, substitutions and alterations may be made herein withoutdeparting from the scope of the present disclosure.

What is claimed is:
 1. An operation method of a first user equipment(UE) supporting direct communications in a communication network, theoperation method comprising: obtaining scheduling information configuredfor the direct communications from a first base station, wherein thefirst UE belongs to coverage of the first base station; identifyingmodulation and coding scheme (MCS) information and radio resourceinformation included in the scheduling information; and transmitting, toa second UE, a first message to which a MCS indicated by the MCSinformation is applied through radio resources indicated by the radioresource information.
 2. The operation method of claim 1, wherein astate of the first UE is a radio resource control (RRC) connected stateor a RRC idle state.
 3. The operation method of claim 1, wherein thefirst base station and a second base station share the schedulinginformation, and the second UE belongs to coverage of the second basestation.
 4. The operation method of claim 1, wherein the radio resourcesindicated by the radio resource information are configured based on aspeed of a vehicle in which the first UE is located, vehicle density ina zone to which the first UE belongs, or service coverage of the directcommunications.
 5. The operation method of claim 1, wherein the radioresource information indicate radio resources which are selected by thefirst base station in a direct communication resource pool when a mode1manner is used, or the radio resource information indicate the directcommunication resource pool when a mode2 manner is used.
 6. Theoperation method of claim 1, wherein the MCS information indicate a MCSindex or a MCS range each of them is configured by the first basestation.
 7. The operation method of claim 1, wherein the MCS indicatedby the MCS information is configured based on a speed of a vehicle inwhich the first UE is located, vehicle density in a zone to which thefirst UE belongs, or service coverage of the direct communications. 8.The operation method of claim 1, wherein communications between thefirst base station and the first UE are performed through a Uuinterface, and the direct communications between the first UE and thesecond UE are performed through a PC5 interface.
 9. The operation methodof claim 1, wherein the first base station is a first roadside unit(RSU) belonging to a vehicle communication network, the first UE is afirst onboard unit (OBU) belonging to the vehicle communication network,and the second UE is a second OBU belonging to the vehicle communicationnetwork.
 10. The operation method of claim 1, further comprising:obtaining, from the first base station, a direct communication resourcepool; performing a monitoring operation on radio resources belonging tothe direct communication resource pool; and receiving, from the secondUE, a second message based on the monitoring operation.
 11. Theoperation method of claim 1, further comprising: requesting, to thefirst base station, allocation of additional radio resources for thedirect communications when the radio resources are unavailable;obtaining, from the first base station, additional radio resourceinformation; and transmitting, to the second UE, a third message throughthe additional radio resources indicated by the additional radioresource information.
 12. The operation method of claim 11, wherein thefirst UE requests the allocation of the additional radio resources tothe first base station based on a random access procedure, a schedulingrequest procedure of a physical uplink control channel (PUCCH), or abuffer status report (BSR) procedure.
 13. The operation method of claim11, wherein the additional radio resources are selected among remainingradio resources except for radio resources, which are used fortransmitting the first message, in the direct communication resourcepool.
 14. An operation method of a first user equipment (UE) supportingdirect communications in a communication network, the operation methodcomprising: when the direct communications between the first UE and asecond UE are ended, transmitting a first message requesting end of thedirect communications to a first base station; and performing, for theend of the direct communications, a release operation of radio resourceswith the first base station or a release operation of radio resourcecontrol (RRC) connection with the first base station, wherein the firstUE belongs to coverage of the first base station, the first UE operatesin a RRC connected state when the release operation of the radioresources is performed, or the first UE operates in a RRC idle statewhen the release operation of the RRC connection is performed.
 15. Theoperation method of claim 14, further comprising: when the directcommunications between the first UE which operates in the RRC connectedstate and the second UE are requested, requesting allocation of radioresources for the direct communications to the first base station;obtaining radio resource information from the first base station; andtransmitting a second message to the second UE through radio resourcesindicated by the radio resource information.
 16. The operation method ofclaim 14, further comprising: when the direct communications between thefirst UE which operates in the RRC idle state and the second UE arerequested, selecting radio resources in a direct communication resourcepool which is obtained from the first base station; and transmitting athird message to the second UE through the selected radio resources. 17.The operation method of claim 16, wherein the direct communicationresource pool is configured based on a speed of a vehicle in which thefirst UE is located, vehicle density in a zone to which the first UEbelongs, or service coverage of the direct communications.
 18. Theoperation method of claim 16, wherein the direct communication resourcepool is shared in the first base station and a second base station, andthe second UE belongs to coverage of the second base station.
 19. Theoperation method of claim 16, wherein a modulation and coding scheme(MCS) which is applied to the third message is configured based on aspeed of a vehicle in which the first UE is located, vehicle density ina zone to which the first UE belongs, or service coverage of the directcommunications.
 20. The operation method of claim 14, wherein the firstbase station is a first roadside unit (RSU) belonging to a vehiclecommunication network, the first UE is a first onboard unit (OBU)belonging to the vehicle communication network, and the second UE is asecond OBU belonging to the vehicle communication network.